[ 源代码： node-d3-ease ]
软件包：node-d3-ease（1.0.5-5）
Easing functions for smooth animation
Easing is a method of distorting time to control apparent motion in animation. It is most commonly used for slow-in, slow-out. By easing time, animated transitions are smoother and exhibit more plausible motion.
Node.js is an event-based server-side JavaScript engine.